1. Field of the Invention
The present disclosure herein relates to a semiconductor memory device, and more particularly, to a nonvolatile memory device.
2. Description of the Related Art
As a nonvolatile memory device, a flash memory device is a kind of Electrical Erasable Programmable Read Only Memory (EEPROM) where a plurality of memory regions are erased or programmed through a one-time programming operation. Typical EEPROMs enable one memory region to be erased or programmed only once. This denotes that flash memory devices may operate at a faster and more effective speed than when systems using the flash memory devices read and write different memory regions at the same time. All the types of flash memories and EEPROMs are worn after a specific number of erasure operations due to the deterioration of a charge storage means that is used to store data or the wear of a dielectric layer surrounding the charge storage means.
Flash memory devices store information in a silicon chip in a method that does not require a power source in retaining the information which is stored in the silicon chip. This denotes that information is retained without consuming a power source when the power source supplied to a chip is shut off. Additionally, flash memory devices provide resistance to physical impact and a fast read access time. Because of these characteristics, the flash memory devices are generally used as the storage devices of systems that receive a power source from a battery.